package net;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;


public class TcpEchoServer {
    private ServerSocket serverSocket=null;
    public TcpEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }
    public void start() throws IOException {
        System.out.println("服务器启动!");
        ExecutorService service = Executors.newCachedThreadPool();
        while(true){
            Socket clientSocket = serverSocket.accept();//serverSocket用于帮助clientSocket建立连接
            //使用多线程来实现多个客户端连接服务器
//            Thread t= new Thread(()->{
//                try {
//                    processConnection(clientSocket);
//                } catch (IOException e) {
//                    e.printStackTrace();
//                }
//            });
//            t.start();
            //使用线程池
            service.submit(()->{
                try {
                    processConnection(clientSocket);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            });
        }
    }
    //针对一个连接,提供处理逻辑
    private void processConnection(Socket clientSocket) throws IOException {
        //先打印一下客户端的信息
        System.out.printf("[%s:%d] 客户端上线!\n",clientSocket.getInetAddress(),clientSocket.getPort());
        //获取到socket中持有的流对象
        try(InputStream inputStream = clientSocket.getInputStream();//TCP是全双工的通信,一个socket对象既可以读也可以写
            OutputStream outputStream = clientSocket.getOutputStream()){
            //使用Scanner包装一下inputStream ,就可以更方便的读取这里的请求数据了
            Scanner scanner = new Scanner(inputStream);
            PrintWriter printWriter = new PrintWriter(outputStream);
            while(true){
                //1.读取请求并解析
                if(!scanner.hasNext()){
                    //如果scanner无法读取出数据,说明客户端关闭了连接,导致服务器读到了"末尾"
                    break;
                }
                String request = scanner.next();
                //2.根据请求计算响应
                String response = process(request);
                //3.把响应写回客户端
                //此处可以按照字节数组直接写,也可以有另一种写法
//                outputStream.write(response.getBytes());
                printWriter.println(response);
                printWriter.flush();//刷新缓冲区

                //4.打印日志
                System.out.printf("[%s:%d] req=%s,resp=%s\n",clientSocket.getInetAddress(),clientSocket.getPort(),request,response);
            }
        }catch(IOException e){
            e.printStackTrace();
        }finally{//只要是方法执行完毕了,就会执行close代码
            //连接失败打印日志
            System.out.printf("[%s:%d] 客户端下线!\n",clientSocket.getInetAddress(),clientSocket.getPort());
            clientSocket.close();//客户端socket需要手动关闭
        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer server = new TcpEchoServer(9090);
        server.start();
    }
}
